Artefacts after rendering
The head is using Material.006 for the skin except for those areas coloured dark.
The dark areas (faces) have material.021 assigned to them!


Just a note to add:
Your mesh is using flat shading on all the faces (this is probably why you are needing 61.000+ vertices just for one ear).

I would suggest you set all faces to smooth shading: in Edit mode select all then open the Faces menu with Ctrl F and choose the Shade Smooth option.